Optimize codegen slightly calling wasm functions

Currently wasm-calls work with `Result<T, Trap>` internally but `Trap`
is an enum defined in `wasmtime-runtime` which is actually quite large.
Since traps are supposed to be rare this commit changes these functions
to return a `Box<Trap>` which is un-boxed later up in the `wasmtime`
crate within a `#[cold]` function.

crates/runtime/src/traphandlers/windows.rs

@@ -74,7 +74,7 @@ unsafe extern "system" fn exception_handler(exception_info: PEXCEPTION_POINTERS)
     })
 }
 
-pub fn lazy_per_thread_init() -> Result<(), Trap> {
+pub fn lazy_per_thread_init() -> Result<(), Box<Trap>> {
     // Unused on Windows
     Ok(())
 }